Continuous pulping apparatus



p 22, 1954 J. P. RICH CONTINUOUS PULPING APPARATUS Filed Sept. 21, 1962United States Patent 3,150,038 CGNTINUQUS PULPlNlG APhARATUS John P.Rich, Nashua, NH, assignor, by mesue assignments, to Improved MachineryEnd, a corporation of Delaware Filed Sept. 21, 1962, Ser. No. 225,264Claims. (Cl. 162-237) This invention relates to the continuous pulpingof fibrous material; more particularly, to apparatus of the type shownin Patent Nos. 2,878,116 and 2,878,117.

In those patents is described and claimed continuous pulping apparatusincluding an upright vessel having reciprocable foraminous solidparticle lifting means, in the form of a perforated helical or fiatpiston end surface, for compacting and advancing upwardly through thevessel in columnar form, wood chips or other particles fed onto thepiston face, with the liquid in the vessel passing freely through theperforations of the piston face as it reciprocates.

Although the structure shown in said patents has proved to be highlysatisfactory and commercially successful when fed with wood chipsselected as to their size, clifficulties have arisen in cases whereinthe material fed onto the piston face encompasses an extreme range ofsizes, particularly when there is a considerable portion of large chipshaving flat surfaces in combination with material which may best becharacterized as relatively small slivers of wood. With such a wood chipmixture, there may arise a relatively high degree of sealing of theperforations of the piston face during upward advance thereof, so thatthe piston may tend to stall in the direction of its upward movement.This, in turn, reduces the efficiency of the apparatus, or makesnecessary the application of higher power to the piston, or both.

It is the object of tie present invention to provide a solution to theabove mentioned problem, by providing a wood chip particle advancingmember having a novel surface configuration, with projections makingpossible a greater liquid flow rate through the perforations thereof.

For the purpose of fully explaining further features and objects of thepresent invention, reference is now made to the following detaileddescription of preferred embodiments thereof, together with theaccompanying drawings, wherein:

FIG. 1 is a cross-sectional elevation showing the particle compactingand advancing structure of Patent No. 2,878,116 with novel surfaceconfiguration according to the present invention;

FIG. 2 is an isometric view of the piston portion of FIG. 1;

FIG. 3 is an enlarged isometric view of a portion of the prior artpiston surface showing typical wood chips jammed against it;

FIG. 4 is an enlarged isometric view of a portion of the piston surfaceof the present invention, showing typi cal wood chips supported thereonwithout jamming;

FIGS. 5 and 6 are, respectively, isometric and sectional views of amodification of the piston surface of FIGS. 1, 2 and 4;

FIGS. 7 and 8 are, respectively, plan and sectional views of anothermodification of the piston surface of FIGS. 1, 2 and 4; and

FIGS. 9 and 10 are, respectively, plan and sectional views of stillanother modification of the piston surface of FIGS. 1, 2 and 4.

As best shown in FIGS. 1 through 3, the novel advancing means of PatentNo. 2,878,116 includes a foraminous screw means mounted for rotationaland reciprocatory movement through a limited distance relatively to thelength of the vessel within the reaction vessel 22 3,153,933 PatentedSept. 22, l94

near the lower end thereof by means of a shaft 36 extending verticallythrough the bottom of said vessel generally axially thereof. Morespecifically, said foraminous screw means comprises a single turnhelical piston plate 32 having therein a plurality of perforations 34sufficient in number to allow substantially free passage of the liq idtherethrough but of small enough size to prevent passage of the chips orother fibrous material. Furthermore, the step of such helical surface isclosed by a flat plate 36 extending vertically between its upper andlower edges 38 and 4t and the peripheral edge thereof is positionedclosely adjacent the inner Walls of the reaction vessel 22 so thatpassage of chips into the bottom portion of said reaction vessel 22; maybe prevented.

For feeding the pressurized mixture of chips and liquid to the uppersurface of said plate, a tubular member 42 having its inner wallconcentric with and spaced from shaft 3% is mounted on the lower surfaceof said helical plate 32 extending downwardly therefrom, thus providinga central aperture 44 between the upper and lower radial edges 38 and 40respectively of said helical plate and extending radially from saidshaft to said member in the lower portion of the helical surface nearsaid lower edge 4d. Said movable member 42 is positioned closely withina fixed tubular member 43 mounted in the lower end of reaction vessel 22and extending both upwardly therefrom to overlap the downwardlyextending edge of movable tubular member 42 and downwardly therefrom toprovide a connection to inlet valve 24 through pipe 46, the lower end ofsaid fixed member being provided with a suitable seal 48.

The lower end of shaft 3%) extends into a hydraulic cylinder 50 mountedbeneath the lower end of reaction vessel 22 and forms the pistonthereof, said cylinder 50 being provided with an inlet pipe 52 connectedto a suitable source of fluid pressure to raise said shaft with thehelical plate 32 to reciprocate said plate, the force of the vesselpressure against the area of the upper end of said shaft being greatenough to rapidly lower the plate when the pressure in cylinder Stl isexhausted, the pressure vessel 22 in such circumstances acting as anaccumulator to provide the necessary force at a rapid rate. Suitablemeans (not shown) for alternately connecting pipe 52 to its source ofpressure and to exhaust may be provided to reciprocate helical plate 32at any desired rate. For rotating shaft 39 to rotate plate 32 in suchdirection as shown by the arrow in FIG. 1, a gear 54 is mounted on shaft3%) for reciprocatory movement relatively thereto as by a heyway, and isdriven through a pinion 56 by a hydraulic motor 58 operated from asuitable source of pressure (not shown).

In operation, the solid particle-liquid mixture or slurry is fed intothe reaction vessel 22 by a centrifugal pump (not shown) so that it willbe pressurized before entering said vessel. The mixture thus passesthrough the passageway formed between shaft 36 and tubular members 42and 43, and finally outwardly through aperture 44 into the lower end ofthe reaction vessel 22 above the perforated helical plate 32. During arun, the reaction vessel is kept full of chips to maintain a compactedelongated mass or zone thereof, the individual chips moving slowlyupwardly as they are reduced to pulp and discharged through mechanism 26at the top of the reaction vessel.

During the feeding of the slurry into reaction vessel 22, the helicalplate 32 is both rotated at a rate of say 6 revolutions per minute asshown by the arrow in FIG. 1 and reciprocated for a short distanceaxially thereof at a rate of say 12 strokes per minute as shown by thereference numeral Elia in FlG. l to provide an axial component ofmovement of the chips fed through aperture t") 44 to move them upwardlyto the bottom of the mass of chips in the reaction vessel and compactthem thereon and advance them therethrough by exerting force onlyagainst the chips at the bottom end of said mass or zone.

Since the mass of chips fills the reaction vessel and its bottom extendsdownwardly toward the helical plate, such rotational and reciprocatorymovement acts on the bottom of said mass of chips to advance it upwardlyat a desired uniform average rate as well as to compact it, and makes itpossible for the helical plate 32 to move the mass of chips upwardlywithout exerting extraordinarily high pressures on the chips, as toohigh pressures seriously damage the chips and cause a substantialreduction in the quality of the resulting pulp. The digested chips aredischarged as pulp through mechanism at the top of the vessel while atthe same time the mixture of chips and liquid is continuously fed intothe bottom of the reaction vessel beneath the mass of chips throughaperture 44. Preferably, the limited reciprocatory movement is arrangedto function normally to successively advance the mass of chips, therotational movement acting normally to feed the chips outward throughaperture 44- below the mass of chips. This may be accomplished byarranging the hydraulic pressure on motor 58 so that it stalls when therotating helical plate comes into firm contact with the mass of chips.Since, with uniform chips, the liquid component of the mixture passesfreely through the perforations in helical plate 32 during suchreciprocation or rotation, neither the reciprocatory nor rotationalmovement will affect the movement of the liquid so that the chips may beadvanced independently thereof.

The upward movement of plate 32 due to the pressure in hydrauliccylinder St? is relatively slow, occupying say 90% of the total cycle,while the downward movement due to the pressure of the vessel acting onthe end of shaft 30 is much more rapid, occupying but about of thecycle. This is made possible by using the vessel in effect as ahydraulic accumulator. Such rapid down ward movement forces the liquidunder plate 32 to move rapidly through the perforations 34, thusflushing away any solid particles that may have become lodged in or overthe perforations 34.

As is shown in FIG. 3 however, a wood chip mixture having a considerableproportion of large fiat chips, particularly in combination with smallslivers and the like, sealing of the perforations 34 tends to occur onupward movement of the piston face 32, such that liquid flow throughsaid piston is restricted to a substantial degree. This restriction inflow is caused by the fiat surfaces of the large chips lying with theflat faces over the perforations 34, and with the areas between thelarge chips being filled with slivers and other debris of small piecesof wood chips. According to the present invention, a novel surfaceconfiguration is provided on the surface of piston 32 which willdecrease the effect of chip sealing upon upward movement of the pistonto the extent it is no longer a problem. The invention may accomplishsuch result by means of one or more of a variety of surfaceconfigurations, two of which are shown in FIGS. 1, 2 and 4.

Referring to those figures, the two projection means shown, either ofwhich may be used independently of the other, comprise a multiplicity ofdiscrete protuberances 60 distributed between perforations 34 generallyuniformly throughout the surface of the piston plate 32, and a pluralityof generally radially extending eddy bars 72, 74, 76, 78 each extendingfrom the center of the plate 32 to its outer rim.

The protuberances. 60, as best shown in FIG. 4 are tapered in form, sothat their tnansverse cross sectional area increases progressively fromits top downward for at least a portion thereof so that jamming of awood chip between adjacent protuberances cannot occur. With suchprotuberances, a multiplicity of channels are in (l effect providedbetween the protuberances along the surface of plate 32 for liquid flowtherealong beneath the bottom of particles such as large wood clipssupported on the tips of the protuberances. The protuberances shown inFIGS. 1, 2 and 4 may be constructed by utilizing drops of weld metalwelded to the surface of plate 32, but other structures may be used aswell, such as tapered studs 64 welded to plate 32 (FIGS. 9 and 10),circular grooves 66 cut in plate 32 providing channels connecting aplurality of perforations 34 (FIGS. 7 and 8), or a plurality of grooves68 extending radially of a plurality of perforations 34 to provideliquid channels along the surface of plate 32 beneath Wood chips orother particles supported thereon (FIGS. 5 and 6). With suchprotuberances, when the piston surface 32 is moved upward to advance thecolumn of Wood chips, the flow of liquid downwardly through perforations34 caused thereby will tend to cause the wood chips to be sucked againstthe surface of the piston. However, the protuberances with channelstherebetween will prevent the chips from sealing the perforations 34,because liquid will be able to flow along the channels provided and intoand through perforations 34.

The eddy bars 72, 74, 76, 78 operate on a somewhat different principalby reason of the circular flow of the liquid on plate 32 caused byeither the inflow velocity of liquid from aperture 44 or by the rotationof the plate 32 or both. This causes an eddy on the downwstream side ofa bar such as is shown by the circular arrow in FIG. 4. Such an eddywill cause the large chips which are first drawn down onto the plate 32to be arranged in a random manner with many of the chips edgewise to theplate. Thus fewer of the holes 34 are covered by large fiat chips andthere is less opportunity for small slivers and the like to seal up theremaining perforated area. Thus liquid flow will be increased by reasonof the change in average alignment of chips to a position less parallelwith plate 32 than would otherwise be the case.

Thus the invention provides novel means effective to improve continuouspulping apparatus of the reciprocating piston type such as is shown inPatent Nos. 2,878,116 and 2,878,117. Various modifications of theinvention, not shown herein, within the spirit of the invention and thescope of the appended claims, will occur to those skilled in the art.

I claim:

1. In apparatus for the continuous treatment of the solid particlecomponent of a solid particle-liquid mixture in an upright elongatedvessel, means for feeding said mixture into the lower entrance end ofsaid vessel and advancing the solid particle component thereof upwardlythrough said vessel substantially independently of the movement of saidliquid in said vessel including a piston having a vertical central axisand a circular surface extending generally in a horizontal plane acrosssubstantially the entire cross section of said vessel, said pistonhaving a multiplicity of perforations distributed throughout its surfaceand a plurality of generally radially extending eddy bars projectingfrom its surface in a direction parallel to said axis and means forrotating said piston about its central axis to move said eddy bars in adirection generally perpendicular thereto to reduce solid particleinteference with at least some of said perforations for free movement ofsaid liquid therethrough.

2. Ln apparatus for the continuous treatment of the wood chip componentof a wood chipdiquid mixture in an upright elongated vessel, means forfeeding said mixture into the lower entrance end of said vessel andadvancing the wood chip component thereof upwardly through said vesselsubstantially independently of the movement of said liquid in saidvessel, said means including a piston having a wall extending generallyin a horizontal plane across said vessel with a multiplicity of throughperforations for flow of the liquid,

through said wall, and with an imperforate wood chip contactingoperating surface extending continuously between and around said throughperforations, said imperforate surface having a multiplicity ofprotuberances thereon providing channels between said protuberances forliquid flow along said channels and beneath the bottom of wood chips incontact with and supported directly by said imperforate surfaceincluding said protuberances, and means for reciprocating said piston,said wood chips being in contact with and supported directly on saidimperforate surface including its protuberances upon upward movement ofsaid piston for free flow of said liquid through said perforations.

3. In apparatus as claimed in claim 2, wherein a multiplicity ofdiscrete protuberances are provided between said through perforations,providing a multiplicity of channels between said protuberances.

4. In apparatus as claimed in claim 2, wherein said piston has acircular operating surface with a central axis, and wherein said pistonsurface has a plurality of eddy bars projecting therefrom in a directionparallel to said axis, said eddy bars extending generally radially alongsaid surface for a major portion of the radius thereof and furtherincluding means for rotating said piston.

5. In apparatus as claimed in claim 3, wherein the transverse crosssectional area of each of said protuberances increases progressivelyfrom its top downward for at least a portion of said protuberance.

References Cited in the file of this patent UNITED STATES PATENTS1,259,048 Roberts Mar. 12, 1918 1,860,836 Gustin May 31, 1932 2,878,116C-arlsmith Mar. 17, 1959

2. IN APPARATUS FOR THE CONTINUOUS TREATMENT OF THE WOOD CHIP COMPONENTOF A WOOD CHIP-LIQUID MICTURE IN AN UPRIGHT ELONGATED VESSEL, MEANS FORFEEDING SAID MIXTURE INTO THE LOWER ENTRANCE END OF SAID VESSEL ANDADVANCING THE WOOD CHIP COMPONENT THEREOF UPWARDLY THROUGH SAID VESSELSUBSTANTIALLY INDEPENDENTLY OF THE MOVEMENT OF SAID LIQUID IN SAIDVESSEL, SAID MEANS INCLUDING A PISTON HAVING A WALL EXTENDING GENERALLYIN A HORIZONTAL PLANE ACROSS SAID VESSEL WITH A MULTIPLICITY OF THROUGHPEROFORATIONS SFOR FLOW OF THE LIQUID THROUGH SAID WALL, AND WITH ANIMPERFORATE WOOD CHIP CONTACTING OPERATING SURFACE EXTENDINGCONTINUOUSLY BETWEEN AND AROUND SAID THROUGH PERFORATION, SAIDIMPERFORATE SURFACE HAVING A MULTIPLICTY OF PROTUBERANCES THEREONPROVIDING CHANNELS BETWEEN SAID PROTUBERANCES FOR LIQUID FLOW ALONG SAIDCHANNELS AND BENEATH THE BOTTOM OF WOOD CHIPS IN CONTACT WITH ANDSUPPORTED DIRECTLY BY SAID IMPERFORATE SURFACE INCLUDING SAIDPROTUBERANCES, AND MEANS FOR RECIPROCATING SAID PISTON, SAID WOOD CHIPSBEING IN CONTACT WITH AND SUPPORTED DIRECTLY ON SAID IMPERFORATE SURFACEINCLUDING ITS PROTUBERANCES UPON UPWARD MOVEMENT OF SAID PISTON FOR FREEFLOW OF SAID LIQUID THROUGH SAID PERFORATIONS.